Heat exchanger tube having integrated thermoelectric devices

ABSTRACT

A heat exchanger for a vehicle is shown, wherein the heat exchanger includes a plurality of tubes having integrated thermoelectric devices disposed thereon to facilitate heat transfer between the tubes and an atmosphere surrounding the tubes.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.11/497,695, filed Aug. 2, 2006, titled HEAT EXCHANGER TUBE HAVINGINTEGRATED THERMOELECTRIC DEVICES, the entire contents of which areincorporated by reference herein and made a part of this specification.

BACKGROUND

1. Field

The present invention relates to a heat exchanger tube and moreparticularly to a heat exchanger tube having integrated thermoelectricdevices to increase a thermal efficiency of the heat exchanger.

2. Description of Related Art

An air-cooled fin-type heat exchanger is very well known. Heatexchangers are used for changing the temperature of various workingfluids, such as an engine coolant, an engine lubricating oil, an airconditioning refrigerant, and an automatic transmission fluid, forexample. The heat exchanger typically includes a plurality of spacedapart fluid conduits or tubes connected between an inlet tank and anoutlet tank, and a plurality of heat exchanging fins disposed betweenadjacent conduits. Air is directed across the fins of the heat exchangerby a cooling fan or a motion of a vehicle, for example. As the air flowsacross the fins, heat in a fluid flowing through the tubes is conductedthrough the walls of the tubes, into the fins, and transferred into theair.

One of the primary goals in heat exchanger design is to achieve thehighest possible thermal efficiency. Thermal efficiency is measured bydividing the amount of heat that is transferred by the heat exchangerunder a given set of conditions (amount of airflow, temperaturedifference between the air and fluid, and the like) by the theoreticalmaximum possible heat transfer under those conditions. Thus, an increasein the rate of heat transfer under a given set of conditions results ina higher thermal efficiency.

Typically, to improve thermal efficiency, the airflow must be improvedand/or a pressure drop through the heat exchanger must be reduced.Improved heat exchanger performance can be accomplished by forming thefins and/or louvers on the fins at a predetermined angle in a manneralso well known in the art. Pressure drop is associated with the changein airflow direction caused by the louvered fins. A higher air pressuredrop can result in a lower heat transfer rate. Various types of fin andlouver designs have been disclosed in the prior art with the object ofincreasing the heat exchanger efficiency by making improvements in thefins, louvers, and airflow pattern.

Examples of these prior art fin and louver designs include an additionof fin rows in order to increase the amount of air encountered by theheat exchanger. Other designs include louvers formed at an angle to thefin wall, rather than square to the fin wall. Further, the prior artdiscloses heat exchangers with multiple changes of airflow direction.Air flows through the louvers until a middle transition piece orturnaround rib is reached. The air then changes direction and flowsthrough exit louvers to exit the heat exchanger. Fin design continues toplay an important role in increasing heat exchanger efficiency.

A thermoelectric device can be used to transfer heat between fluids,such as from air flow to a fluid in a fluid conduit, for example. Thethermoelectric device includes a hot side and a cold side, wherein oneof the hot side and the cold side is in communication with each of thefluids. A heat transfer efficiency of the thermoelectric devicedecreases as a difference in temperature between the hot side and thecold side thereof increases.

It would be desirable to produce a tube for a heat exchanger having anintegrated thermoelectric device whereby a thermal efficiency of theheat exchanger is maximized.

SUMMARY

Harmonious with the present invention, a tube for a heat exchangerhaving an integrated thermoelectric device whereby a thermal efficiencyof the heat exchanger is maximized has surprisingly been discovered.

In one embodiment, a tube for a heat exchanger comprises a hollowconduit having a wall, a first end, and a spaced apart second end; and athermoelectric device in thermal communication with the wall of theconduit to facilitate heat transfer between a first fluid in the conduitand a second fluid outside of the conduit.

In another embodiment, a heat exchanger comprises at least one heatexchanger tank; a hollow tube having a wall, a first end, and a spacedapart second end, the tube in fluid communication with the at least oneheat exchanger tank; a thermoelectric device in thermal communicationwith the wall of the tube; and a heat exchanger fin in thermalcommunication with the thermoelectric device.

In another embodiment, a heat exchanger comprises at least one heatexchanger tank; a plurality of hollow tubes, each tube having a wall, afirst end, and a spaced apart second end, the tubes in fluidcommunication with the at least one heat exchanger tank and adapted toconvey a first fluid; a plurality of heat exchanger fins disposedadjacent the tubes and in thermal communication with a second fluid; anda plurality of thermoelectric devices, at least one thermoelectricdevice disposed between the tubes and the fins to facilitate heattransfer therebetween.

BRIEF DESCRIPTION OF THE DRAWINGS

The above, as well as other objects and advantages of the invention,will become readily apparent to those skilled in the art from readingthe following detailed description of a preferred embodiment of theinvention when considered in the light of the accompanying drawings inwhich:

FIG. 1 is an end sectional view of a tube for a heat exchanger inaccordance with an embodiment of the invention;

FIG. 2 is an end sectional view a heat exchanger using the tube of FIG.1;

FIG. 3 is a side sectional view of a tube for a heat exchanger inaccordance with another embodiment of the invention; and

FIG. 4 is a front sectional view of a heat exchanger in accordance withanother embodiment of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The following detailed description and appended drawings describe andillustrate various exemplary embodiments of the invention. Thedescription and drawings serve to enable one skilled in the art to makeand use the invention, and are not intended to limit the scope of theinvention in any manner.

FIG. 1 shows a cylindrical tube 10 for a heat exchanger 40 illustratedin FIG. 2. The tube 10 has an outer wall 12 with a substantiallycircular cross-sectional shape. Other cross-sectional shapes can be usedas desired. The wall 12 is preferably formed from copper or steel;however, other materials may be used to form the wall 12 withoutdeparting from the scope and spirit of the invention. The wall 12 formsa hollow interior portion 14.

A thermoelectric device (TED) 16 surrounds and is in thermalcommunication with the wall 12. The TED 16 includes a first heattransfer surface 18 and a second heat transfer surface 20. The firstheat transfer surface 18 is in thermal communication with the wall 12.The second heat transfer surface 20 is in thermal communication with aplurality of fins 22 surrounding the TED 16.

The TED 16 is in electrical communication with a control system (notshown). The control system controls an electric current sent to the TED16. When a current is delivered in one direction, one of the first heattransfer surface 18 and the second heat transfer surface 20 generatesthermal energy and the other of the first heat transfer surface 18 andthe second heat transfer surface 20 absorbs thermal energy. When thecurrent is reversed, the one of the first heat transfer surface 18 andthe second heat transfer surface 20 which was generating thermal energynow absorbs thermal energy, and the other of the first heat transfersurface 18 and the second heat transfer surface 20 now generates thermalenergy. When the current is increased, a heating and cooling capacity ofthe TED 16 is increased. Likewise, when the current is decreased, theheating and cooling capacity of the TED 16 is decreased.

The TED 16 may be any conventional device such as: those produced byMarlow Industries, Inc. of Dallas, Tex.; the thermoelectric systemsdescribed in U.S. Pat. No. 6,539,725 to Bell; a quantum tunnelingconverter; a Peltier device; a thermo ionic module; a magneto caloricmodule; an acoustic heating mechanism; a solid state heat pumpingdevice; and the like; for example; or any combination of the deviceslisted above. Although a single thermoelectric device is shown, it isunderstood that additional thermoelectric devices can be used, asdesired.

In use, a first fluid (not shown) is caused to flow through the hollowinterior portion 14 of the tube 10. The first fluid can be anyconventional fluid such as air or a coolant such as a water-glycolcoolant, for example. The first fluid contains thermal energy which istransferred to the wall 12. Current is supplied to the TED 16, whichcauses the first heat transfer surface 18 of the TED 16 to absorbthermal energy from the wall 12. Simultaneously, the second heattransfer surface 20 of the TED 16 generates thermal energy. The thermalenergy generated by the second heat transfer surface 20 of the TED 16 istransferred to the fins 22. A second fluid (not shown) is caused to flowacross and contact the fins 22. The second fluid can be any conventionalfluid such as air, for example. The thermal energy transferred from thesecond heat transfer surface 20 of the TED 16 to the fins 22 istransferred to the second fluid.

FIG. 3 shows a tube 60 for a heat exchanger (not shown) having a firstwall 62, a second wall 64, a fluid inlet 66, and a fluid outlet 68. Thetube 60 shown is a flat tube for use in a flat tube heat exchanger.However, tubes having other shapes and for use in other types of heatexchangers, such as cross flow heat exchangers, shell and tube heatexchangers, or counter flow heat exchangers, for example, can be used asdesired without departing from the scope and spirit of the invention.The walls 62, 64 are preferably formed from copper or steel. However,other materials may be used to form the walls 62, 64 as desired. Thefirst wall 62, the second wall 64, and a pair of side walls (not shown)cooperate to form a hollow interior portion 70.

A first thermoelectric device (TED) 72 is disposed adjacent to and is inthermal communication with the first wall 62. The first TED 72 includesa first heat transfer surface 74 and a second heat transfer surface 76.The first heat transfer surface 74 is in thermal communication with thefirst wall 62. The second heat transfer surface 76 is in thermalcommunication with a plurality of fins 78 disposed adjacent to the firstTED 72.

A second thermoelectric device (TED) 80 is disposed adjacent to and isin thermal communication with the second wall 64. The second TED 80includes a first heat transfer surface 82 and a second heat transfersurface 84. The first heat transfer surface 82 is in thermalcommunication with the second wall 64. The second heat transfer surface84 is in thermal communication with a plurality of fins 86 disposedadjacent to the second TED 80.

The TEDs 72, 80 may be any conventional devices such as: those producedby Marlow Industries, Inc. of Dallas, Tex.; the thermoelectric systemsdescribed in U.S. Pat. No. 6,539,725 to Bell; a quantum tunnelingconverter; a Peltier device; a thermo ionic module; a magneto caloricmodule; an acoustic heating mechanism; a solid state heat pumpingdevice; and the like; for example; or any combination of the deviceslisted above. Although two thermoelectric devices are shown, it isunderstood that a single or additional thermoelectric devices can beused, as desired. Further, it is understood that the side walls of thetube 60 may include additional TEDs if desired. If the side walls of thetube include additional TEDs, a plurality of fins can be disposedadjacent the TEDs as desired.

The first TED 72 and the second TED 80 are in electrical communicationwith a control system (not shown). The control system controls anelectric current sent to the TEDs 72, 80. When a current is delivered inone direction, one of the first heat transfer surfaces 74, 82 and thesecond heat transfer surfaces 76, 84 generates thermal energy and theother of the first heat transfer surfaces 74, 82 and the second heattransfer surfaces 76, 84 absorbs thermal energy. When the current isreversed, the one of the first heat transfer surfaces 74, 82 and thesecond heat transfer surfaces 76, 84 which was generating thermal energynow absorbs thermal energy, and the other of the first heat transfersurfaces 74, 82 and the second heat transfer surfaces 76, 84 nowgenerates thermal energy. When the current is increased, a heating andcooling capacity of the TEDs 72, 80 is increased. Likewise, when thecurrent is decreased, the heating and cooling capacity of the TEDs 72,80 is decreased.

In use, a first fluid (not shown) is caused to flow through the hollowinterior portion 70 of the tube 60. The first fluid can be anyconventional fluid such as air or a coolant such as a water-glycolcoolant, for example. The first fluid contains thermal energy which istransferred to the first wall 62 and the second wall 64. Current issupplied to the TEDs 72, 80, which causes the first heat transfersurfaces 74, 82 of the TEDs 72, 80 to absorb thermal energy from thefirst wall 62 and the second wall 64. Simultaneously, the second heattransfer surfaces 76, 84 of the TEDs 72, 80 generate thermal energy. Thethermal energy generated by the second heat transfer surfaces 76, 84 ofthe TEDs 72, 80 is transferred to the fins 78, 86. A second fluid (notshown) is caused to flow across and contact the fins 78, 86. The secondfluid can be any conventional fluid such as air, for example. Thethermal energy transferred from the second heat transfer surfaces 76, 84of the TEDs 72, 80 to the fins 78, 86 is transferred to the secondfluid.

FIG. 4 shows a heat exchanger 100 in accordance with another embodimentof the invention. The heat exchanger 100 includes a first header 102 anda spaced apart second header 104. A plurality of cylindrical tubes 106are disposed between the first header 102 and the second header 104. Thetubes have walls 108 with a substantially circular cross-sectionalshape. Other cross-sectional shapes can be used as desired. The walls108 are preferably formed from copper or steel. However, other materialsmay be used to form the walls 108 without departing from the scope andspirit of the invention. The walls 108 form hollow interior portions 110and include a fluid inlet 107 and a fluid outlet 109.

A thermoelectric device (TED) 112 surrounds and is in thermalcommunication with each of the walls 108. Each TED 112 includes a firstheat transfer surface 114 and a second heat transfer surface 116. Thefirst heat transfer surface 114 is in thermal communication with thewall 108 of the corresponding tube 106. The second heat transfer surface116 is in thermal communication with a plurality of fins 120 disposedbetween each adjacent tube 106.

Each TED 112 is in electrical communication with a control system (notshown). The control system controls an electric current sent to the TED112. When a current is delivered in one direction, one of the first heattransfer surface 114 and the second heat transfer surface 116 generatesthermal energy and the other of the first heat transfer surface 114 andthe second heat transfer surface 116 absorbs thermal energy. When thecurrent is reversed, the one of the first heat transfer surface 114 andthe second heat transfer surface 116 which was generating thermal energynow absorbs thermal energy and the other of the first heat transfersurface 114 and the second heat transfer surface 116 now generatesthermal energy. Additionally, when the current is increased, a heatingand cooling capacity of the TED 112 is increased. Likewise, when thecurrent is decreased, the heating and cooling capacity of the TED 112 isdecreased.

The TEDs 112 may be any conventional devices such as: those produced byMarlow Industries, Inc. of Dallas, Tex.; the thermoelectric systemsdescribed in U.S. Pat. No. 6,539,725 to Bell; a quantum tunnelingconverter; a Peltier device; a thermo ionic module; a magneto caloricmodule; an acoustic heating mechanism; a solid state heat pumpingdevice; and the like; for example; or any combination of the deviceslisted above. Although a single thermoelectric device is shown disposedadjacent each of the tubes 106, it is understood that additionalthermoelectric devices can be used, as desired.

In use, a first fluid (not shown) is caused to flow from the secondheader 104 through the fluid inlets 107 into the hollow interiorportions 110 of the tubes 106. The first fluid can be any conventionalfluid such as air or a coolant such as a water-glycol coolant, forexample. The first fluid contains thermal energy which is transferred tothe walls 108. Current is supplied to each TED 112, which causes thefirst heat transfer surface 114 of each TED 112 to absorb thermal energyfrom the wall 108 of the corresponding tube 106. Simultaneously, thesecond heat transfer surface 116 of each TED 112 generates thermalenergy. The thermal energy generated by the second heat transfer surface116 of each TED 112 is transferred to the fins 120. A second fluid (notshown) is caused to flow across and contact the fins 120. The secondfluid can be any conventional fluid such as air, for example. Thethermal energy transferred from the second heat transfer surface 116 ofeach TED 112 to the fins 120 is transferred to the second fluid. Thefirst fluid flows out of the fluid outlets 109 and into the first header102.

From the foregoing description, one ordinarily skilled in the art caneasily ascertain the essential characteristics of this invention and,without departing from the spirit and scope thereof, can make variouschanges and modifications to the invention to adapt it to various usagesand conditions.

1. A heat exchanger comprising: at least one fluid channel; a pluralityof hollow tubes, each of the plurality of tubes having a wall, a firstend, and a spaced apart second end, wherein a hollow interior portion ofeach of the plurality of tubes is in fluid communication with the atleast one fluid channel; a plurality of thermoelectric devices, each ofthe plurality of thermoelectric devices comprising a first heat transfersurface and a second heat transfer surface, wherein the first heattransfer surface of each of the plurality of thermoelectric devices isin thermal communication with at least a portion of the wall of at leastone of the plurality of tubes; and a plurality of heat exchanger fins,each of the plurality of heat exchanger fins in thermal communicationwith the second heat transfer surface of at least one of the pluralityof thermoelectric devices, wherein the plurality of heat exchanger finsare configured to substantially increase a surface area of thermalcommunication between the plurality of thermoelectric devices and aworking fluid flowing outside the plurality of hollow tubes beyond thesurface area of thermal communication of the heat exchanger without theplurality of heat exchanger fins.
 2. The heat exchanger of claim 1,further comprising a control system in electrical communication with theplurality of thermoelectric devices, the control system configured tocontrol a direction of electric current delivered to the plurality ofthermoelectric devices.
 3. The heat exchanger of claim 2, wherein thecontrol system is configured to control a variable electric currentdelivered to the plurality of thermoelectric devices.
 4. The heatexchanger of claim 1, wherein at least one of the plurality ofthermoelectric devices is disposed around the wall of at least one ofthe tubes.
 5. The heat exchanger of claim 1, wherein the hollow interiorportion of the plurality of tubes is configured to convey a first fluid,and the heat exchanger is configured to convey a second fluid outsidethe plurality of tubes.
 6. The heat exchanger of claim 5, wherein thefirst fluid is a liquid, and the second fluid is a gas.
 7. The heatexchanger of claim 1, wherein the heat exchanger is a flat tube heatexchanger.
 8. The heat exchanger of claim 1, wherein the heat exchangeris a cross flow heat exchanger.
 9. The heat exchanger of claim 1,wherein the heat exchanger is a shell and tube heat exchanger.
 10. Theheat exchanger of claim 1, wherein the heat exchanger is a counter flowheat exchanger.
 11. The heat exchanger of claim 1, wherein the controlsystem is configured to control the direction of the electric currentdelivered to the plurality of thermoelectric devices in order to selectbetween a first mode, in which thermal energy is transferred from thewall to the plurality of heat exchanger fins, and a second mode, inwhich thermal energy is transferred from the plurality of heat exchangerfins to the wall.
 12. A method of manufacturing a heat exchanger, themethod comprising: providing a plurality of hollow tubes, each of theplurality of tubes having a wall, a first end, and a spaced apart secondend, wherein a hollow interior portion of each of the plurality of tubesis in fluid communication with the at least one fluid channel; providinga plurality of thermoelectric devices, each of the plurality ofthermoelectric devices comprising a first heat transfer surface and asecond heat transfer surface; placing the first heat transfer surface ofeach of the plurality of thermoelectric devices is in thermalcommunication with at least a portion of the wall of at least one of theplurality of tubes; and providing a plurality of heat exchanger fins;placing each of the plurality of heat exchanger fins in thermalcommunication with the second heat transfer surface of at least one ofthe plurality of thermoelectric devices, wherein the plurality of heatexchanger fins are configured to substantially increase a surface areaof thermal communication between the plurality of thermoelectric devicesand a working fluid flowing outside the plurality of hollow tubes beyondthe surface area of thermal communication of the heat exchanger withoutthe plurality of heat exchanger fins.
 13. The method of claim 12,further comprising operatively connecting a control system to theplurality of thermoelectric devices, the control system configured tocontrol a direction of electric current delivered to the plurality ofthermoelectric devices.
 14. The method of claim 13, wherein the controlsystem is configured to control a variable electric current delivered tothe plurality of thermoelectric devices.
 15. The method of claim 12,wherein at least one of the plurality of thermoelectric devices isdisposed around the walls of the tubes.
 16. The method of claim 12,wherein the plurality of heat exchanger fins extend radially outwardlyfrom outer surfaces of the thermoelectric devices.
 17. The method ofclaim 12, wherein the hollow interior portion of the plurality of tubesis configured to convey a first fluid, and the heat exchanger isconfigured to convey a second fluid outside the plurality of tubes. 18.The method of claim 17, wherein the first fluid is a liquid, and thesecond fluid is a gas.
 19. The method of claim 12, wherein the heatexchanger is one of a flat tube heat exchanger, a cross flow heatexchanger, a shell and tube heat exchanger, and a counter flow heatexchanger.
 20. The method of claim 12, wherein the control system isconfigured to control the magnitude of the electric current delivered tothe at least one thermoelectric device in order to select a heating andcooling capacity of the at least one thermoelectric device.